Help..tpms Light And Rear Locker Stuck?

hmb2016 · May 30, 2011

Hey guys... I drove down the interstate about 400 miles today and ran into a pretty serious problem.. about 200 miles into it, my TPMS light came on.. so i pulled over to the gas station and as i tried to turn in, my electronic locking differential was engaged... 200 miles of straight smooth highway and it still has not disengaged..btw my tires were all perfectly ok.. could the tpms light be related to the rear differential getting stuck? not even sure why it engaged itself in the first place.

My truck is a 2008 gmc sierra 1500 2wd with the 5.3

Can anyone help me figure out whats goin on and what i should do? the local dealer here is closed today

dlstewart01 · May 31, 2011

Hey guys... I drove down the interstate about 400 miles today and ran into a pretty serious problem.. about 200 miles into it, my TPMS light came on.. so i pulled over to the gas station and as i tried to turn in, my electronic locking differential was engaged... 200 miles of straight smooth highway and it still has not disengaged..btw my tires were all perfectly ok.. could the tpms light be related to the rear differential getting stuck? not even sure why it engaged itself in the first place.
My truck is a 2008 gmc sierra 1500 2wd with the 5.3

Can anyone help me figure out whats goin on and what i should do? the local dealer here is closed today

Is this electronic locking diff something you installed. The truck did not come with one.

If you have a G80, it is a mechanical locker.

nickvrebel · May 31, 2011

factory does not have an electronic locking differential and I don't see that in your mod list. Assuming you are referring to the G80 Mechanical locking differential from the factory then it sounds like it has failed. You need to get it looked at and see if it can be repaired or if it needs replacement. Should be covered under the 5yr/100,000 mile powertrain warranty.

AirForceAngler · May 31, 2011

Could a drastic difference in rear tire pressures have set off his Traction Control light or Stabilitrak light somehow and that is what he's thinking is his electronic locker?

dlstewart01 · May 31, 2011

Sometimes changing out the diff fluid will help.

LOCKING DIFFERENTIAL LUBRICANT (SERVICE INFORMATION) #91-4-109

SUBJECT: LOCKING DIFFERENTIAL (G80) LUBRICANT - (SERVICE INFORMATION)

VEHICLES AFFECTED: ALL LIGHT TRUCKS EQUIPPED WITH G80 REAR AXLE ALL YEARS

Some light duty trucks equipped with locking rear axles (G80) may exhibit rear axle chatter, especially when turning a corner from a stop.

This condition of alternate engagement and disengagement of clutches in differential assembly is usually caused by contaminated axle lubricant.

To correct this condition, drain and refill the rear axle with SAE 75W-90 GL5 (P/N 12378261). The use of any additive in locking rear axles (G80) is not recommended. Rear axle additives are designed for use in limited slip differentials which are normally installed in cars. All light duty trucks equipped with RPO G80 make use of a locking differential and the use of additives will delay the engagement of the locking mechanism and may decrease axle life.VEHICLES/COMPONENTS INVOLVED: ----------------------------- Some light duty trucks equipped with locking rear axles, RPO G80.

SERVICE PARTS INFORMATION:

Part Number Description ----------- ------------------ 12678261 Lubricant, Rear Axle (1 litre)

Parts are currently available through CANSPO.

WARRANTY INFORMATION:

As specified in Light Duty Truck Maintenance Schedules, locking rear axle fluid drain and refill is required owner maintenance at the first engine oil change. Failure to drain and refill the rear axle as specified may contribute to a later axle chatter condition. Refer to the appropriate Light Duty Truck Maintenance Schedule or service manual, section OB, for further details on change intervals.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.

nickvrebel · May 31, 2011

Could a drastic difference in rear tire pressures have set off his Traction Control light or Stabilitrak light somehow and that is what he's thinking is his electronic locker?

I wasn't even reading his initial post right, you are correct - if the TPMS light is activated then he needs to check the pressure in the tires, a large difference will be enough to activate the G80 and cause this issue, however, the G80 will unlock at speeds in excess of 20 mph.

dlstewart01 · May 31, 2011

Could a drastic difference in rear tire pressures have set off his Traction Control light or Stabilitrak light somehow and that is what he's thinking is his electronic locker?

I wasn't even reading his initial post right, you are correct - if the TPMS light is activated then he needs to check the pressure in the tires, a large difference will be enough to activate the G80 and cause this issue, however, the G80 will unlock at speeds in excess of 20 mph.

It takes 100 RPM difference between rear wheels to engage the G80. I doubt air pressure would be enough to cause the G80 to engage.

AirForceAngler · May 31, 2011

It takes 100 RPM difference between rear wheels to engage the G80. I doubt air pressure would be enough to cause the G80 to engage.

I'm just guessing but since he's saying his "electronic locker" he may have been getting a Stabilitrak light on the dash, not really the rear end locking up. Could a big difference in tire pressures activate that? Until he comes back and explains what he meant by an electronic locker, we're all just guessing but I'm thinking it was the traction control or stabilitrak.

hmb2016 · May 31, 2011

sorry guys,

yes i am referring to the g80... not an electronic one. i have no mods done to my truck in that department... well i spoke to the dealer and they said that the "spider gears have seperated" so they are ordering parts for me..

as far as the tpms, my air pressure was all the same so there was no difference in pressure for it to trip. and i was going 70 mph on a straight interstate for 300+ miles

hmb2016 · May 31, 2011

also i never had a stabilitrack light on or a check engine light.. just a tpms light about the same time the locker started giving me trouble

Ianf · May 31, 2011

I think the TPMS light also comes on when wheel tempature is too high. The locker failure may has caused this after a short distance at that speed as one wheel might tend to drag and overheat. Did the DIC show a low tire pressure or just a general failure of the TPMS?